title: BIG1, a brefeldin A-inhibited guanine nucleotide-exchange protein regulates neurite development via PI3K-AKT and ERK signaling pathways.
abstract: The elongation of neuron is highly dependent on membrane trafficking. Brefeldin A (BFA)-inhibited guanine nucleotide-exchange protein 1 (BIG1) functions in the membrane trafficking between the Golgi apparatus and the plasma membrane. BFA, an uncompetitive inhibitor of BIG1 can inhibit neurite outgrowth and polarity development. In this study, we aimed to define the possible role of BIG1 in neurite development and to further investigate the potential mechanism. By immunostaining, we found that BIG1 was extensively colocalized with synaptophysin, a marker for synaptic vesicles in soma and partly in neurites. The amount of both protein and mRNA of BIG1 were up-regulated during rat brain development. BIG1 depletion significantly decreased the neurite length and inhibited the phosphorylation of phosphatidylinositide 3-kinase (PI3K) and protein kinase B (AKT). Inhibition of BIG1 guanine nucleotide-exchange factor (GEF) activity by BFA or overexpression of the dominant-negative BIG1 reduced PI3K and AKT phosphorylation, indicating regulatory effects of BIG1 on PI3K-AKT signaling pathway is dependent on its GEF activity. BIG1 siRNA or BFA treatment also significantly reduced extracellular signal-regulated kinase (ERK) phosphorylation. Overexpression of wild-type BIG1 significantly increased ERK phosphorylation, but the dominant-negative BIG1 had no effect on ERK phosphorylation, indicating the involvement of BIG1 in ERK signaling regulation may not be dependent on its GEF activity. Our result identified a novel function of BIG1 in neurite development. The newly recognized function integrates the function of BIG1 in membrane trafficking with the activation of PI3K-AKT and ERK signaling pathways which are critical in neurite development.
authors.affiliation: Laboratory of Pharmacology and Toxicology, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, China.
authors.forename: C
authors.initials: C
authors.lastname: Zhou
authors.forename: C
authors.initials: C
authors.lastname: Li
authors.forename: D
authors.initials: D
authors.lastname: Li
authors.forename: Y
authors.initials: Y
authors.lastname: Wang
authors.forename: W
authors.initials: W
authors.lastname: Shao
authors.forename: Y
authors.initials: Y
authors.lastname: You
authors.forename: J
authors.initials: J
authors.lastname: Peng
authors.forename: X
authors.initials: X
authors.lastname: Zhang
authors.forename: L
authors.initials: L
authors.lastname: Lu
authors.forename: X
authors.initials: X
authors.lastname: Shen
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000196:embryology / Q000254:growth & development / Q000378:metabolism; D020662:Guanine Nucleotide Exchange Factors / Q000502:physiology*; D006801:Humans; D020935:MAP Kinase Signaling System / Q000502:physiology*; D016501:Neurites / Q000378:metabolism*; D058539:Phosphatidylinositol 3-Kinase / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000502:physiology
chemical_list: C578854:ARFGEF1 protein, rat; D020662:Guanine Nucleotide Exchange Factors; D058539:Phosphatidylinositol 3-Kinase; D051057:Proto-Oncogene Proteins c-akt
keywords: 3-(4,5)-dimethylthiahiazo(-z-y1)-3,5-di-phenytetrazoliumromide; ADP-ribosylation factor; AKT; Arf; BFA; BFA-inhibited guanine nucleotide-exchange protein 1; BIG1; DIV; Dulbecco’s modification of Eagle’s medium; ECL; EDTA; ER; ERK; GDP; GEF; GTP; LDH; MAP2; MTT; PI3K; RIPA; RT; RT-qPCR; SD; Sprague–Dawley; TGN; brefeldin A; days in vitro; endoplasmic reticulum; enhanced chemiluminescence; ethylenediaminetetraacetic acid; extracellular signal-regulated kinase; guanine nucleotide-exchange factor; guanosine diphosphate; guanosine triphosphate; lactate dehydrogenase; microtubule-associated protein 2; neurite; outgrowth; phosphatidylinositide 3-kinase; protein kinase B; radio immunoprecipitation assay; reverse-transcribed polymerase chain reaction; room temperature; trans-Golgi network